Spectral flame photometer burner



Sept 29, 1970 Filed out. 14, 1966 2 Sheets-Sheet 1 INVENTORS JA c K ISREELI F IG 2 #0 E: /2\, r 2% /4 2 I E R I; I H MW W W /44 /0- 20 ii W 32 EDWARD W. LA RRABEE A 77' ORNE Y Sept. 29, 1970 J. ISREELI ETAL SPECTRAL FLAME PHOTOMETER BURNER 2 Sheets-Sheet 2 Filed Oct. 14, 1966 zfffrff 1 INVENTORS By JACK ISREELI EDWARD w. LARRABEE ATTORNEY United States Patent 3,531,203 SPECTRAL FLAME PHOTOMETER BURNER Jack Isreeli, Mamaroneck, and Edward W. Larrabee,

Bronxville, N.Y., assignors to Technicon Instruments Corporation, Chauncey, Ardsley, N.Y., a corporation of New York Filed Oct. 14, 1966, Ser. No. 586,685 Int. Cl. F23d 13/00, 13/40 US. Cl. 356-87 11 Claims ABSTRACT OF THE DISCLOSURE This invention relates to spectral flame burners for providing a spectral flame for the quantitative analysis of various liquids with respect to one or more substances therein.

Spectral flame burners which atomize a sample liquid and carry the sample liquid into a main flame for vaporization are well known. In most of the prior art burners, both the fuel gas and the combustion supporting gas were supplied under significant pressure to the burner. Such burners are illustrated in U.S. Pats. 2,562,874; 2,714,833; and 3,137,759. These burners all use the gas flow at the base of the flame over a sample tube to aspirate the sample up the sample tube into the flame. There the sample is broken into droplets, some of which are small, some of which are large. When the large droplets are vaporized the flame is pulsed thermally and mechanically and the result is a flame which is uneven in intensity. Other burners are illustrated in US. Pats. 2,753,753 and 2,858,729. These burners use a preatomization arrangement wherein oxygen under pressure flows over a sample tube to aspirate the sample into the oxygen flow and to break the sample into droplets. The droplets containing oxygen flow strikes a bafile which contacts and collects the larger droplets. However the mixing of the oxygen flow with the fuel gas occurs at the base of the flame. This mixing tends to be uneven, and the result is a flame which is uneven in intensity.

As previously mentioned, these burners required both the fuel gas and the combustion supporting gas supplies to be under significant pressure, which made them unsuitable for use with fuel gas as supplied by utilities companies, since such gas is normally supplied at a relatively low pressure, egg. inches of water or .14 p.s.i.

It is, therefore, an object of the invention to provide a spectral flame burner which is adapted to utilize a fuel gas supplied at a very low pressure, and which will pass only relatively small droplets of sample into the flame.

A feature of the invention is the provision of a spectral flame burner which has a means for atomizing the sample into a flow of a first gas and for withdrawing from such flow any relatively large droplets of such sample; means for mixing the sample containing flow of first gas with a flow of a second gas; and means for burning the mixture of sample, first gas and second gas.

These and other objects, features and advantages will become apparent upon consideration of the following specification taken in conjunction with the accompanying drawing in which:

FIG. 1 is a top view of the main assembly of a flame photometer embodying this invention;

3,531,203 Patented Sept. 29, 1970 FIG. 2 is a front view of the photometer of FIG. 1;

FIG. 3 is a bottom view of the burner assembly of the photometer of FIG. 1;

FIG. 4 is a view in cross-section taken along the plane 4-4 of FIG. 3; and

FIG. 5 is a view in cross-section of the sample inlet assembly taken along the plane 5--5 of FIG. 4.

As seen in FIGS. 1 and 2 the flame photometer main assembly includes a burner assembly 10; a mirror assembly 12; a sample detector assembly 14; an infrared flame detector assembly 16; and a flame igniter assembly 1 8. A chimney which fits over the burner, mirror and igniter assemblies has not been shown.

The burner assembly 10 includes a tubular main body 20, having in longitudinal axial alignment a lower mixing chamber 22, an upper burner tube receiving bore 24, two intermediate chambers 26 and 28, an upper annular flange 30 and a lower annular flange 32. A base plate 34 is releasably sealed to the lower flange 32 by a plurality of thumbscrews 36 and an O-ring 38. The main body also has three bosses and bores for three fittings, i.e., sample, air and gas. The gas fitting 40 is mounted into the main body on a transverse axis which is displaced slightly from a radius of the main body so that the inner wall of the mixing chamber 22 intersects the longitudinal axis of the gas fitting at an angle which is less than The sample fitting 42 is disposed in the same horizontal plane as the gas fitting 40 and has a longitudinal axis which is chordal to the mixing chamber 22. The air fitting 44 is disposed in the same vertical plane as, and above, the sample fitting 42. The bore of the air fitting 44 communicates with a vertical longitudinal bore 46 provided in a rib 48 formed in the wall of the main body. The lower end of the bore 46 communicates with the bore 50 in the main body through which the sample fitting is disposed. The upper end of the bore 46 communicates with a bore 52 in a top plate 54 which is secured to the upper flange 30 by machine screws, not shown. A short tube 56 is disposed within the upper portion of the bore 46 to restrict the flow of air from the air fitting 44 to the bore 52.

A burner tube 58 is sealed within the upper bore 24 of the main body and extends upwardly, through and beyond a central bore 60 in the top plate 54. The upper end of the burner tube is closed by a burner cap 62 which has a plurality of perforations 64 and a burner tip 66.

An auxiliary air manifold block 68 is disposed on the top plate 54 around the upper end of the burner tube. The block is closed by an annular plate 70, whose upper surface is level with the upper surface of the burner cap 62. The block 68 includes a central bore 71, an outer lower flange 72 which rests on the top plate 54 and is sealed thereto by an O-ring 74 and a plurality of machine screws, not shown, an intermediate annular recess 76 to support a chimney, not shown, and an O-ring 78 to seal the block to the chimney. The block also includes an outer lower annular cavity 80, an inner lower annular cavity 82, and an upper annular cavity 84. The bore 52 communicates with the cavities 82 and 80 by a gap 56 between the plate 54 and the block, and the cavity 82 communicates with the cavity 84 by a plurality of longi tudinal bores 88. The cavity 84 has an upper annular opening 90. An O-ring 92 seals the gap between the exterior of the burner tube 58 and the central bore 71.

The sample fitting 42 includes an atomizer body having a longitudinal bore 102 and a diametrical bore 104. The inlet end is internally threaded to receive an atomizer capillary assembly 106, and the outlet end is internally threaded to receive an atomizer tip 108. The capillary assembly 106 includes a leur lock 110 having a central bore through which an outer tube 112 is sealed and whose right end is sealed within the left portion of the bore of the tip 108; and an inner tube 114 sealed within the outer tube 112, and whose right end projects beyond the outer tube within the right portion of the bore of the tip 108. A plurality of radial holes 116 are provided in the tip 108. Thus, air may pass through the diametrical holes 104, through the gap between the body 100 and the outer tube 112, through the gap between the body 100 and the tip 108, through the radial holes 116, through the gap between the tip 108 and the inner tube 114, past the right end of the inner tube 114 and out the right end of the tip 108.

The sample liquid which is to be flame photometrically examined is displaced into the left end of the capillary tube by a positive displacement pump such as is shown in US Pat. No. 2,935,028. Two O-rings 118, 120, seal the bore 104 into communication with the bore 46. Thus when compressed air is provided at the air fitting 44, most of that air passes downwardly through the bore 46, through the bore 104, past the right end of the capillary tube 114 and out the tip 108. As the air passes the end of the capillary tube it atomizes the sample liquid being discharged therefrom and carries droplets of the sample liquid into the mixing chamber 22. Since the sample fitting is located on a chord with respect to the mixing chamber, the air and droplet flow strikes the inner surface of mixing chamber and swirls around within the chamber in a clockwise direction, as shown in FIG. 3. The larger, heavier droplets of sample liquid strike and are retained on the wall of the mixing chamber, and gradually flow down the wall to the base plate 34 and thence out a depressed drain 122 to waste. It will be appreciated that should it be desired to economize on sample liquid, the collected flow from the drain may be recycled through the pump and sample inlet fitting.

The fuel gas fitting 40 includes a body 124 and a tube sealed therethrough, which is coupled to a source of relatively low pressure fuel gas. The outlet end 128 of the tube 126 is closed and a longitudinal line of radial bores 130 is provided for the discharge of gas into the mixing chamber. The line of bores is oriented to be on the lee side of the tube with respect to the clockwise flow of the relatively high pressure air from the atomizer tip 108, so that a space of relatively low pressure is formed adjacent these bores, into which space the relatively low pressure gas may flow. The air, sample vapour and fuel gas swirl around in the mixing chamber 22 and uniformly intermix. The mixture, still swirling, rises up through the intermediate chambers 28 and 26 into the burner tube 58. Three symmetrically disposed fins 136 are provided projecting from the inner surface of the burner tube to deflect the swirling flow into a linear flow up the burner tube and out the perforations 64. Since the tube 126 is at an acute angle to the clockwise air and sample vapor flow, any sample which settles out on the tube will be blown along the tube to the body 124 and will drain off onto the wall of the mixing chamber.

When compressed air is provided at the air fitting 44, some of that air passes upwardly through the bore 46 and the constricting tube 56 into the two lower annular cavities 82 and 80, and thence into the upper annular cavity 84 out the annular opening 90 to provide a uniform sheath of air around the main flame from the perforations 64. This sheath stabilizes the main flame by girdling it and by supplying excess oxygen for complete combustion.

The burner tip 64 projects into the blue cone of the fiame and is heated thereby. The tip is in thermal conduction with the burner cap 62 and at the start of operation, rapidly brings the cap to thermal equilibrium to stabilize the preheating of the gas mixture.

The mirror assembly 12 serves to reflect the spectral light from the flame to the sample detector assembly 16. The particular embodiment of flame photometer herein described is adapted to measure three constituents concurrently, e.g. potassium and sodium unknowns against a lithium standard. For this purpose the detector assembly includes a heat sink block in which three detectors are disposed. A filter assembly includes three filters, one for each respective wavelength which is to be measured.

The infrared flame detector assembly 16 includes a cell which provides a voltage output in response to heat. This cell is coupled through an amplifier and a latching circuit to a warning buzzer, not shown, and a solenoid valve in the supply line to the fuel gas inlet. The flame igniter assembly 18 includes a solenoid operated linkage which is operable to swing an arm 140 having a resistance coil 142 mounted thereon from the position shown in FIG. 1 to a position over the burner cap. In operation, the system is energized by a mains switch. The warning buzzer will be energized since there is no flame. An ignition switch, when operated, energizes the solenoid linkage to swing the resistance coil 142 over the burner cap and also energizes the coil; and operates the solenoid valve to admit fuel gas through the fuel gas inlet. Upon ignition of the flame, the flame detector turns off the buzzer and latches on the relay controlling the gas solenoid valve so that the ignition switch may be released, deenergizing the ignition coil and its solenoid so that the ignitor assembly swings out of the flame.

While we have shown and described the preferred embodiment of the invention, it will be understood that the invention may be embodied otherwise than as herein specifically illustrated or described, and that certain changes in the form and arrangement of parts and in the specific manner of practicing the invention may be made without departing from the underlying idea or principles of this invention within the scope of the appended claims.

What is claimed is:

1. A method of operating a spectral flame photometer burner comprising: providing a flow of a first gas; introducing a sample liquid into said flow of first gas whereby said flow atomizes said liquid into droplets; introducing said flow of first gas and droplets into a chamber and directing said flow to produce a swirling motion within said chamber such that the relatively large droplets strike and are collected on the interior wall surfaces of said chamber; obstructing said flow of said first gas and droplets within said chamber to provide a relatively low pressure region in said chamber; introducing a second gas into said flow of first gas and relatively small droplets at said relatively low pressure region and intermixing said gases and droplets within said chamber; and burning sain mixture of said first and second gases and droplets at a station remote from the station whereat said intermixing is performed.

2. A method according to claim 1 including the further step of introducing said first gas at a relatively high pressure and said second gas at a relatively low pressure.

3. A method according to claim 1 including the further step of converting said swirling motion of said mixture of gases and droplets to a rectilinear flow prior to burning at said remote station.

4. A spectral flame photometer burner comprising: an upstanding burner tube having an outlet and an inlet; a substantially circular mixing chamber coupled to said inlet; means including a nozzle disposed within said chamber for introducing a first gas containing droplets of a sample to be analyzed into said chamber under a relatively high pressure, said nozzle having its longitudinal axis oriented on a geometric chord other than the diameter of said chamber, such that said first gas containing said sample droplets has a path of flow which strikes and is caused to swirl around along the interior wall surface of said chamber whereby relatively large droplets of said sample are collected on said interior wall surface; means located in the path of flow of said first gas containing said sample droplets for providing in its lee a region of relatively low pressure in said chamber; means disposed within said chamber at said relatively low pressure region for introducing a second gas under relatively low pressure to mix into said flow of said first gas containing said 5 sample droplets; and means for passing said mixture of said first gas containing said sample droplets and said second gas to said outlet of said burner tube whereat said mixture is ignited.

5. A burner according to claim 4 wherein a tube is disposed within said nozzle, a sample liquid transmitted through said tube being atomized into droplets by said first gas and carried along by said first gas, any relatively large droplets striking said interior wall of said chamber and collecting thereon.

6. A burner according to claim 4 wherein said providing means and said means for introducing said serond gas comprise a tube having a closed end and disposed substantially radially into said chamber, said tube having at least one radial bore through the lee wall thereof, so that a space of relatively low pressure is formed adjacent said radial bore.

7. A burner according to claim 4 wherein said mixing chamber is coaxial with said burner tube, further including a plurality of longitudinally extending baflles disposed within said burner tube, whereby said swirling path of flow of said mixture of said first gas, said sample droplets and said second gas rises from said mixing chamber into said burner tube and is deflected by said baflies into a rectilinear path of flow.

8. A burner according to claim 4 further including a perforated plate capping said burner tube, through which said mixture of said first gas, said sample droplets and said second gas passes, and above which, upon ignition, said gases will form a flame; said plate having a central projection which extends into such flame and is heated thereby, whereby said plate, upon ignition of such flame,

6 is rapidly brought to and maintained at an elevated temperature.

9. A burner according to claim 4 further including ignition means disposed above the top of said burner tube, said ignition means being normally disposed away from said top of said burner tube and mounted to be swung over said top of said burner tube to ignite the gases exiting therefrom.

10. A burner according to claim 9 wherein said ignition means includes a resistance heating coil.

11. A burner according to claim 4 further including an annular outlet means coaxial with and surrounding said outlet of said burner tube, and means for supplying additional first gas through said annular outlet means to provide a sheath of such first gas around said mixture of said first gas, said sample droplets and said second gas exiting from said outlet of said burner tube.

References Cited UNITED STATES PATENTS 2,836,097 5/1958 Garman 35687 X FOREIGN PATENTS 712,700 7/1954 Great Britain.

RONALD L. WIBERT, Primary Examiner F. L. EVANS, Assistant Examiner US. Cl. X.-R. 

